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Sourcecode: alsa-driver version File versions

vmaster.c

/*
 * Virtual master and slave controls
 *
 *  Copyright (c) 2008 by Takashi Iwai <tiwai@suse.de>
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License as
 *  published by the Free Software Foundation, version 2.
 *
 */

#include <linux/slab.h>
#include <sound/core.h>
#include <sound/control.h>
#include <sound/tlv.h>

/*
 * a subset of information returned via ctl info callback
 */
struct link_ctl_info {
      int type;         /* value type */
      int count;        /* item count */
      int min_val, max_val;   /* min, max values */
};

/*
 * link master - this contains a list of slave controls that are
 * identical types, i.e. info returns the same value type and value
 * ranges, but may have different number of counts.
 *
 * The master control is so far only mono volume/switch for simplicity.
 * The same value will be applied to all slaves.
 */
struct link_master {
      struct list_head slaves;
      struct link_ctl_info info;
      int val;          /* the master value */
      unsigned int tlv[4];
};

/*
 * link slave - this contains a slave control element
 *
 * It fakes the control callbacsk with additional attenuation by the
 * master control.  A slave may have either one or two channels.
 */

struct link_slave {
      struct list_head list;
      struct link_master *master;
      struct link_ctl_info info;
      int vals[2];            /* current values */
      unsigned int flags;
      struct snd_kcontrol slave; /* the copy of original control entry */
};

static int slave_update(struct link_slave *slave)
{
      struct snd_ctl_elem_value *uctl;
      int err, ch;

      uctl = kmalloc(sizeof(*uctl), GFP_KERNEL);
      if (!uctl)
            return -ENOMEM;
      uctl->id = slave->slave.id;
      err = slave->slave.get(&slave->slave, uctl);
      for (ch = 0; ch < slave->info.count; ch++)
            slave->vals[ch] = uctl->value.integer.value[ch];
      kfree(uctl);
      return 0;
}

/* get the slave ctl info and save the initial values */
static int slave_init(struct link_slave *slave)
{
      struct snd_ctl_elem_info *uinfo;
      int err;

      if (slave->info.count) {
            /* already initialized */
            if (slave->flags & SND_CTL_SLAVE_NEED_UPDATE)
                  return slave_update(slave);
            return 0;
      }

      uinfo = kmalloc(sizeof(*uinfo), GFP_KERNEL);
      if (!uinfo)
            return -ENOMEM;
      uinfo->id = slave->slave.id;
      err = slave->slave.info(&slave->slave, uinfo);
      if (err < 0) {
            kfree(uinfo);
            return err;
      }
      slave->info.type = uinfo->type;
      slave->info.count = uinfo->count;
      if (slave->info.count > 2  ||
          (slave->info.type != SNDRV_CTL_ELEM_TYPE_INTEGER &&
           slave->info.type != SNDRV_CTL_ELEM_TYPE_BOOLEAN)) {
            snd_printk(KERN_ERR "invalid slave element\n");
            kfree(uinfo);
            return -EINVAL;
      }
      slave->info.min_val = uinfo->value.integer.min;
      slave->info.max_val = uinfo->value.integer.max;
      kfree(uinfo);

      return slave_update(slave);
}

/* initialize master volume */
static int master_init(struct link_master *master)
{
      struct link_slave *slave;

      if (master->info.count)
            return 0; /* already initialized */

      list_for_each_entry(slave, &master->slaves, list) {
            int err = slave_init(slave);
            if (err < 0)
                  return err;
            master->info = slave->info;
            master->info.count = 1; /* always mono */
            /* set full volume as default (= no attenuation) */
            master->val = master->info.max_val;
            return 0;
      }
      return -ENOENT;
}

static int slave_get_val(struct link_slave *slave,
                   struct snd_ctl_elem_value *ucontrol)
{
      int err, ch;

      err = slave_init(slave);
      if (err < 0)
            return err;
      for (ch = 0; ch < slave->info.count; ch++)
            ucontrol->value.integer.value[ch] = slave->vals[ch];
      return 0;
}

static int slave_put_val(struct link_slave *slave,
                   struct snd_ctl_elem_value *ucontrol)
{
      int err, ch, vol;

      err = master_init(slave->master);
      if (err < 0)
            return err;

      switch (slave->info.type) {
      case SNDRV_CTL_ELEM_TYPE_BOOLEAN:
            for (ch = 0; ch < slave->info.count; ch++)
                  ucontrol->value.integer.value[ch] &=
                        !!slave->master->val;
            break;
      case SNDRV_CTL_ELEM_TYPE_INTEGER:
            for (ch = 0; ch < slave->info.count; ch++) {
                  /* max master volume is supposed to be 0 dB */
                  vol = ucontrol->value.integer.value[ch];
                  vol += slave->master->val - slave->master->info.max_val;
                  if (vol < slave->info.min_val)
                        vol = slave->info.min_val;
                  else if (vol > slave->info.max_val)
                        vol = slave->info.max_val;
                  ucontrol->value.integer.value[ch] = vol;
            }
            break;
      }
      return slave->slave.put(&slave->slave, ucontrol);
}

/*
 * ctl callbacks for slaves
 */
static int slave_info(struct snd_kcontrol *kcontrol,
                  struct snd_ctl_elem_info *uinfo)
{
      struct link_slave *slave = snd_kcontrol_chip(kcontrol);
      return slave->slave.info(&slave->slave, uinfo);
}

static int slave_get(struct snd_kcontrol *kcontrol,
                 struct snd_ctl_elem_value *ucontrol)
{
      struct link_slave *slave = snd_kcontrol_chip(kcontrol);
      return slave_get_val(slave, ucontrol);
}

static int slave_put(struct snd_kcontrol *kcontrol,
                 struct snd_ctl_elem_value *ucontrol)
{
      struct link_slave *slave = snd_kcontrol_chip(kcontrol);
      int err, ch, changed = 0;

      err = slave_init(slave);
      if (err < 0)
            return err;
      for (ch = 0; ch < slave->info.count; ch++) {
            if (slave->vals[ch] != ucontrol->value.integer.value[ch]) {
                  changed = 1;
                  slave->vals[ch] = ucontrol->value.integer.value[ch];
            }
      }
      if (!changed)
            return 0;
      return slave_put_val(slave, ucontrol);
}

static int slave_tlv_cmd(struct snd_kcontrol *kcontrol,
                   int op_flag, unsigned int size,
                   unsigned int __user *tlv)
{
      struct link_slave *slave = snd_kcontrol_chip(kcontrol);
      /* FIXME: this assumes that the max volume is 0 dB */
      return slave->slave.tlv.c(&slave->slave, op_flag, size, tlv);
}

static void slave_free(struct snd_kcontrol *kcontrol)
{
      struct link_slave *slave = snd_kcontrol_chip(kcontrol);
      if (slave->slave.private_free)
            slave->slave.private_free(&slave->slave);
      if (slave->master)
            list_del(&slave->list);
      kfree(slave);
}

/*
 * Add a slave control to the group with the given master control
 *
 * All slaves must be the same type (returning the same information
 * via info callback).  The fucntion doesn't check it, so it's your
 * responsibility.
 *
 * Also, some additional limitations:
 * - at most two channels
 * - logarithmic volume control (dB level), no linear volume
 * - master can only attenuate the volume, no gain
 */
int _snd_ctl_add_slave(struct snd_kcontrol *master, struct snd_kcontrol *slave,
                   unsigned int flags)
{
      struct link_master *master_link = snd_kcontrol_chip(master);
      struct link_slave *srec;

      srec = kzalloc(sizeof(*srec) +
                   slave->count * sizeof(*slave->vd), GFP_KERNEL);
      if (!srec)
            return -ENOMEM;
      srec->slave = *slave;
      memcpy(srec->slave.vd, slave->vd, slave->count * sizeof(*slave->vd));
      srec->master = master_link;
      srec->flags = flags;

      /* override callbacks */
      slave->info = slave_info;
      slave->get = slave_get;
      slave->put = slave_put;
      if (slave->vd[0].access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK)
            slave->tlv.c = slave_tlv_cmd;
      slave->private_data = srec;
      slave->private_free = slave_free;

      list_add_tail(&srec->list, &master_link->slaves);
      return 0;
}
EXPORT_SYMBOL(_snd_ctl_add_slave);

/*
 * ctl callbacks for master controls
 */
static int master_info(struct snd_kcontrol *kcontrol,
                  struct snd_ctl_elem_info *uinfo)
{
      struct link_master *master = snd_kcontrol_chip(kcontrol);
      int ret;

      ret = master_init(master);
      if (ret < 0)
            return ret;
      uinfo->type = master->info.type;
      uinfo->count = master->info.count;
      uinfo->value.integer.min = master->info.min_val;
      uinfo->value.integer.max = master->info.max_val;
      return 0;
}

static int master_get(struct snd_kcontrol *kcontrol,
                  struct snd_ctl_elem_value *ucontrol)
{
      struct link_master *master = snd_kcontrol_chip(kcontrol);
      int err = master_init(master);
      if (err < 0)
            return err;
      ucontrol->value.integer.value[0] = master->val;
      return 0;
}

static int master_put(struct snd_kcontrol *kcontrol,
                  struct snd_ctl_elem_value *ucontrol)
{
      struct link_master *master = snd_kcontrol_chip(kcontrol);
      struct link_slave *slave;
      struct snd_ctl_elem_value *uval;
      int err, old_val;

      err = master_init(master);
      if (err < 0)
            return err;
      old_val = master->val;
      if (ucontrol->value.integer.value[0] == old_val)
            return 0;

      uval = kmalloc(sizeof(*uval), GFP_KERNEL);
      if (!uval)
            return -ENOMEM;
      list_for_each_entry(slave, &master->slaves, list) {
            master->val = old_val;
            uval->id = slave->slave.id;
            slave_get_val(slave, uval);
            master->val = ucontrol->value.integer.value[0];
            slave_put_val(slave, uval);
      }
      kfree(uval);
      return 1;
}

static void master_free(struct snd_kcontrol *kcontrol)
{
      struct link_master *master = snd_kcontrol_chip(kcontrol);
      struct link_slave *slave;

      list_for_each_entry(slave, &master->slaves, list)
            slave->master = NULL;
      kfree(master);
}


/**
 * snd_ctl_make_virtual_master - Create a virtual master control
 * @name: name string of the control element to create
 * @tlv: optional TLV int array for dB information
 *
 * Creates a virtual matster control with the given name string.
 * Returns the created control element, or NULL for errors (ENOMEM).
 *
 * After creating a vmaster element, you can add the slave controls
 * via snd_ctl_add_slave() or snd_ctl_add_slave_uncached().
 *
 * The optional argument @tlv can be used to specify the TLV information
 * for dB scale of the master control.  It should be a single element
 * with #SNDRV_CTL_TLVT_DB_SCALE type, and should be the max 0dB.
 */
struct snd_kcontrol *snd_ctl_make_virtual_master(char *name,
                                     const unsigned int *tlv)
{
      struct link_master *master;
      struct snd_kcontrol *kctl;
      struct snd_kcontrol_new knew;

      memset(&knew, 0, sizeof(knew));
      knew.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
      knew.name = name;
      knew.info = master_info;

      master = kzalloc(sizeof(*master), GFP_KERNEL);
      if (!master)
            return NULL;
      INIT_LIST_HEAD(&master->slaves);

      kctl = snd_ctl_new1(&knew, master);
      if (!kctl) {
            kfree(master);
            return NULL;
      }
      /* override some callbacks */
      kctl->info = master_info;
      kctl->get = master_get;
      kctl->put = master_put;
      kctl->private_free = master_free;

      /* additional (constant) TLV read */
      if (tlv && tlv[0] == SNDRV_CTL_TLVT_DB_SCALE) {
            kctl->vd[0].access |= SNDRV_CTL_ELEM_ACCESS_TLV_READ;
            memcpy(master->tlv, tlv, sizeof(master->tlv));
            kctl->tlv.p = master->tlv;
      }

      return kctl;
}
EXPORT_SYMBOL(snd_ctl_make_virtual_master);

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